1. Field of the Invention
The present invention relates to a cable, such as a seismic streamer, including a plurality of chambers forming a necklace float.
It also concerns tools for filling, degassing or connecting the chambers of the cable.
2. Description of the Prior Art
Cables referred to as seismic streamers are conventionally used for marine seismic surveying and carry sensors such as geophones or hydrophones. They are designed to be towed by a ship at sea to acquire seismic signals.
The cables include a plurality of chambers forming a necklace float which must be filled with gas, degassed or connected, according to the depth at which the seismic streamers are to be towed.
FIGS. 1 and 2 show diagrammatically a portion of a prior art cable between two successive chambers A and B of the cable.
As shown in FIGS. 1 and 2, each chamber A, B is generally associated with a filling/degassing orifice 1A, 1B which is specific to it and to which it is connected by a passage 2A, 2B.
Each orifice 1A, 1B cooperates with a screwthreaded closure plug 3A, 3B fitted with an O-ring.
To feed the chamber A the plug 3A is removed and a filling tool 6 is applied to the orifice 1A.
To feed the chamber B the plug 3B is removed and the filling tool 6 is applied to the orifice 1B.
The chamber A or the chamber B is degassed by removing the plug 3A or 3B from the corresponding orifice 1A, 1B.
Thus filling or degassing two successive chambers necessitates manipulation of the two plugs 3A, 3B.
A communication passage 4 is generally provided to connect the two chambers A, B and a stopper 5 fitted with an O-ring opens or closes the duct.
Connecting the two chambers A and B necessitates manipulation of the stopper 5, which constitutes a component separate from the plugs 3A, 3B.
An object of the invention is to propose a simpler design.
More particularly, the invention proposes a design whereby two successive chambers can be filled and degassed or connected via the same orifice.
The cable according to the invention is therefore a marine cablexe2x80x94in particular a seismic streamerxe2x80x94including a plurality of chambers forming a necklace float and means for filling, degassing the chambers and means for connecting two successive chambers, the means including an intervention orifice between the chambers and with which the chambers communicate, in which cable connection of the chambers to the intervention orifice is controlled by two valve mechanisms which each include an obturator pushed by spring means against a communication opening and a guide rod which, when the obturator closes the opening, lies partly in the intervention orifice so that it is possible to push back the rods of the valve mechanisms from the intervention orifice for selective connection of the intervention orifice to one or the other of the two chambers or with both at the same time.
The cable advantageously includes a plug adapted to close the communication orifice, the plug includes a closure base and, aligned with the base, a tapered part which is positioned between the guide rods when the plug is in place in the intervention orifice, and the tapered part has a shape and dimensions such that in a first angular position of the plug relative to the intervention orifice the larger section faces of the tapered part face the guide rods, which are in a position such that their obturators close their communication opening, whereas in another angular position, when they have been turned by one quarter-turn relative to the first angular position, the rods of the valve mechanism bear on the edges of the tapered part so that the obturators of the valve mechanisms are disengaged from the openings that they close, which connects the two chambers.
In particular, the base of the plug can include fixing means for fixing the plug to a tool for disengaging the plug from the intervention orifice or turning it by one quarter-turn. The fixing means can include an internally threaded fixing hole.
The tapered part of the plug advantageously has a cam profile on which the guide rods slide when the plug is turned in the intervention orifice.
The invention also proposes a system including at least one marine cable such as a seismic streamer including a plurality of chambers forming a necklace float and a tool for filling the chambers, one end of which includes a filler nozzle, wherein the cable is a cable of the aforementioned kind and the end, of the filling tool which includes a filler nozzle is adapted to be inserted into an intervention orifice and selectively to push back one or other of the rods of the valve mechanisms when the filling tool is turned one way or the other in the intervention orifice.
The system is advantageously completed by a tool adapted to cooperate with the means for fixing the plug(s) to disengage the plug(s) from the intervention orifice(s) or to turn the plug(s) by one quarter-turn in the orifice(s).
Other features and advantages of the invention will emerge from the following description. The description is purely illustrative and is not limiting on the invention. It should be read in conjunction with the accompanying drawings.